In general, a display device collectively refers to monitors for a TV or a computer, and includes a display element forming an image and a case supporting the display element.
Examples of the display element include a plasma display panel (PDP), a liquid crystal display (LCD), an electrophoretic display, and a cathode-ray tube (CRT). The display element may include an RGB pixel pattern for implementing an image and an additional optical filter.
The optical filter may include at least one of a reflection prevention film for preventing the external light, which is incident from the outside, from being reflected again to the outside, a near IR shield film for shielding the near IR generated in the display element in order to prevent malfunction of electronic devices, such as remote controllers, a color correction film for increasing the color purity by including a color control dye to control a color tone, and an electromagnetic wave shield film for shielding the electromagnetic wave generated in a display element when a display device is driven. Here, the electromagnetic wave shield film includes a transparent substrate and a metal mesh pattern provided on the substrate.
Meanwhile, with regard to the display device, as the spread of IPTVs is accelerated, a need for a touch function that uses hands as a direct input apparatus without a separate input apparatus such as remote controllers is growing. Further, a multi-touch function that is capable of recognizing a specific point and writing is also required.
A touch sensor performing the aforementioned function may be classified into the following types according to the type of detecting a signal.
That is, examples thereof include a resistive type of sensing a position, which is pressed down by pressure, through a change in current or voltage value while a direct current voltage is applied, a capacitive type of using capacitance coupling while an alternating current voltage is applied, an electromagnetic type of sensing a selected position as a change in voltage while a magnetic field is applied, and the like.
Among them, the resistive type and capacitive type touch sensors, which are most extensively spread, recognize the touch by changes in electric contact or capacitance using a transparent conductive film such as an ITO film. However, since the transparent conductive film has a high resistance of 100 ohms/square or more, the sensitivity is lowered when a device is manufactured in a large scale, and as the size of screen is increased, the cost of the ITO film is rapidly increased, and accordingly, it is not easy to achieve commercialization. In order to overcome this, there is an effort to implement an increase in size by using a metal pattern having high conductivity.